Re: çå: çå: [PATCH] iommu/vt-d: Don't reject nvme host due to scope mismatch

From: Lu Baolu
Date: Tue Dec 24 2019 - 01:27:33 EST


Hi Jim,

On 2019/12/24 11:24, Jim,Yan wrote:
-----éäåä-----
åää: Lu Baolu [mailto:baolu.lu@xxxxxxxxxxxxxxx]
åéæé: 2019å12æ23æ 21:05
æää: Jim,Yan <jimyan@xxxxxxxxx>; Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
æé: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
äé: Re: çå: [PATCH] iommu/vt-d: Don't reject nvme host due to scope
mismatch

Hi,

On 2019/12/23 15:59, Jim,Yan wrote:
-----éäåä-----
åää: Jerry Snitselaar [mailto:jsnitsel@xxxxxxxxxx]
åéæé: 2019å12æ20æ 17:23
æää: Jim,Yan <jimyan@xxxxxxxxx>
æé: joro@xxxxxxxxxx; iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx;
linux-kernel@xxxxxxxxxxxxxxx
äé: Re: [PATCH] iommu/vt-d: Don't reject nvme host due to scope
mismatch

On Fri Dec 20 19, jimyan wrote:
On a system with an Intel PCIe port configured as a nvme host
device, iommu initialization fails with

DMAR: Device scope type does not match for 0000:80:00.0

This is because the DMAR table reports this device as having scope 2
(ACPI_DMAR_SCOPE_TYPE_BRIDGE):


Isn't that a problem to be fixed in the DMAR table then?

but the device has a type 0 PCI header:
80:00.0 Class 0600: Device 8086:2020 (rev 06)
00: 86 80 20 20 47 05 10 00 06 00 00 06 10 00 00 00
10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 86 80 00 00
30: 00 00 00 00 90 00 00 00 00 00 00 00 00 01 00 00

VT-d works perfectly on this system, so there's no reason to bail
out on initialization due to this apparent scope mismatch. Add the
class
0x600 ("PCI_CLASS_BRIDGE_HOST") as a heuristic for allowing DMAR
initialization for non-bridge PCI devices listed with scope bridge.

Signed-off-by: jimyan <jimyan@xxxxxxxxx>
---
drivers/iommu/dmar.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c index
eecd6a421667..9faf2f0e0237 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -244,6 +244,7 @@ int dmar_insert_dev_scope(struct
dmar_pci_notify_info *info,
info->dev->hdr_type != PCI_HEADER_TYPE_NORMAL) ||
(scope->entry_type == ACPI_DMAR_SCOPE_TYPE_BRIDGE
&&
(info->dev->hdr_type == PCI_HEADER_TYPE_NORMAL &&
+ info->dev->class >> 8 != PCI_CLASS_BRIDGE_HOST &&
info->dev->class >> 8 != PCI_CLASS_BRIDGE_OTHER))) {
pr_warn("Device scope type does not match for %s\n",
pci_name(info->dev));
--
2.11.0

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Actually this patch is similar to the commit: ffb2d1eb88c3("iommu/vt-d: Don't
reject NTB devices due to scope mismatch"). Besides, modifying DMAR table
need OEM update BIOS. It is hard to implement.


For both cases, a quirk flag seems to be more reasonable, so that unrelated
devices will not be impacted.

Best regards,
baolu

Hi Baolu,
Thanks for your advice. And I modify the patch as follow.

I just posted a patch for both NTG and NVME cases. Can you please take a
look? Does it work for you?

Best regards,
baolu


On a system with an Intel PCIe port configured as a nvme host device, iommu
initialization fails with
DMAR: Device scope type does not match for 0000:80:00.0
This is because the DMAR table reports this device as having scope 2
(ACPI_DMAR_SCOPE_TYPE_BRIDGE):
but the device has a type 0 PCI header:
80:00.0 Class 0600: Device 8086:2020 (rev 06)
00: 86 80 20 20 47 05 10 00 06 00 00 06 10 00 00 00
10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 86 80 00 00
30: 00 00 00 00 90 00 00 00 00 00 00 00 00 01 00 00
VT-d works perfectly on this system, so there's no reason to bail out
on initialization due to this apparent scope mismatch. Add the class
0x06 ("PCI_BASE_CLASS_BRIDGE") as a heuristic for allowing DMAR
initialization for non-bridge PCI devices listed with scope bridge.
Signed-off-by: jimyan <jimyan@xxxxxxxxx>

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index eecd6a421667..50c92eb23ee4 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -244,7 +244,7 @@ int dmar_insert_dev_scope(struct dmar_pci_notify_info *info,
info->dev->hdr_type != PCI_HEADER_TYPE_NORMAL) ||
(scope->entry_type == ACPI_DMAR_SCOPE_TYPE_BRIDGE &&
(info->dev->hdr_type == PCI_HEADER_TYPE_NORMAL &&
- info->dev->class >> 8 != PCI_CLASS_BRIDGE_OTHER))) {
+ info->dev->class >> 16 != PCI_BASE_CLASS_BRIDGE))) {
pr_warn("Device scope type does not match for %s\n",
pci_name(info->dev));
return -EINVAL;


Jim